A swift radio burst is a colossal flash of radio radiation that endures for mere milliseconds, during which it can temporarily surpass every other radio emitter in its galaxy. These flares can be so luminous that their emission can be observed from halfway across the universe, spanning several billion light years away.
The origins of these fleeting and spectacular signals remain elusive. However, researchers now possess an opportunity to examine a fast radio burst (FRB) in unparalleled detail. An international assembly of researchers, including physicists from MIT, have identified a nearby and exceptionally bright fast radio burst approximately 130 million light-years from Earth in the Ursa Major constellation. This is one of the nearest FRBs identified to date, and it also holds the title of the most luminous — so intense that it has garnered the informal nickname, RBFLOAT, meaning “radio brightest flash of all time.”
The intensity of the burst, along with its closeness, is providing scientists with the most intimate view yet at FRBs and their originating surroundings.
“In cosmic terms, this fast radio burst is essentially in our vicinity,” states Kiyoshi Masui, associate professor of physics and a member of MIT’s Kavli Institute for Astrophysics and Space Research. “This provides us with an opportunity to study a relatively typical FRB with incredible intricacy.”
Masui and his associates present their discoveries today in the Astrophysical Journal Letters.
Varied bursts
The clarity of this new detection results from a substantial enhancement to The Canadian Hydrogen Intensity Mapping Experiment (CHIME), a vast array of halfpipe-shaped antennas located in British Columbia. Originally, CHIME was intended to detect and map hydrogen’s distribution throughout the universe. The telescope is also highly sensitive to rapid and bright radio emissions. Since commencing observations in 2018, CHIME has logged around 4,000 fast radio bursts from all corners of the sky. However, the telescope previously struggled to accurately determine the location of each fast radio burst — until now.
CHIME has recently received a significant upgrade in precision, termed CHIME Outriggers — three miniature versions of CHIME, each positioned in various locations across North America. Collectively, the telescopes operate as a single continent-sized system that can hone in on any bright flash that CHIME detects, to accurately ascertain its position in the sky.
“Imagine we are in New York and there’s a firefly in Florida that glows for a thousandth of a second, which is typically how quickly FRBs occur,” explains MIT Kavli graduate student Shion Andrew. “Identifying an FRB within a specific area of its host galaxy is akin to pinpointing not just the tree from which the firefly emerged, but also the specific branch it resides upon.”
The recent fast radio burst marks the initial detection made using the combination of CHIME and the newly completed CHIME Outriggers. Together, the telescope array located the FRB and determined not only the precise galaxy, but also the specific region of the galaxy from which the burst emanated. It appears that the burst originated from the periphery of the galaxy, just outside of a star-forming area. The accurate localization of the FRB is enabling researchers to investigate the environment surrounding the signal for insights into what generates such bursts.
“As we obtain these far more precise observations of FRBs, we can better appreciate the variety of environments from which they arise,” remarks MIT physics postdoc Adam Lanman.
Lanman, Andrew, and Masui are part of the CHIME Collaboration — which encompasses scientists from numerous institutions globally — and are contributors to the new manuscript detailing the findings of this latest FRB detection.
An older boundary
Each of CHIME’s Outrigger stations perpetually surveys the same section of sky as the primary CHIME array. Both CHIME and the Outriggers “listen” for radio flares at exceptionally short, millisecond intervals. Even across several minutes, such accurate monitoring can yield an enormous quantity of data. If CHIME does not detect an FRB signal, the Outriggers automatically eliminate the last 40 seconds of data to accommodate the next batch of measurements.
On March 16, 2025, CHIME detected an exceptionally bright flash of radio emissions, which automatically triggered the CHIME Outriggers to record the data. Initially, the flash was so brilliant that astronomers were uncertain whether it was an FRB or merely a terrestrial occurrence, perhaps caused by a burst of cellular communications.
This theory was dispelled as the CHIME Outrigger telescopes concentrated on the flash and pinpointed its location to NGC4141 — a spiral galaxy within the Ursa Major constellation, approximately 130 million light-years distant, which is surprisingly close to our own Milky Way. This detection ranks among the nearest and brightest fast radio bursts recorded so far.
Subsequent observations in that region indicated that the burst originated from the very outskirts of an active star formation zone. While the precise source of FRBs remains a mystery, scientists’ primary hypothesis points toward magnetars — young neutron stars endowed with extraordinarily powerful magnetic fields that can emit high-energy flares across the electromagnetic spectrum, including in the radio band. Physicists speculate that magnetars inhabit the cores of star-forming regions, where the youngest and most dynamic stars are created. The location of this new FRB, right outside a star-forming area in its galaxy, may imply that the burst originates from a marginally older magnetar.
“These are largely suggestions,” Masui notes. “But the accurate localization of this burst allows us to delve into the details regarding how aged an FRB source could be. If it were situated centrally, it would only be thousands of years old — quite young for a star. This one, being on the fringe, may have had a bit more time to mature.”
No repetitions
Aside from accurately identifying the location of this new FRB in the sky, the researchers also reviewed CHIME data to ascertain whether any similar flares occurred in the same area previously. Since the first FRB was identified in 2007, astronomers have recorded over 4,000 radio flares. The majority of these bursts are unique events. However, a small percentage have been observed to generate repeated signals, illuminating periodically. An even tinier fraction of these repeaters emit in a pattern, resembling a rhythmic heartbeat, before ceasing. A central inquiry surrounding fast radio bursts is whether repeaters and nonrepeaters stem from distinct origins.
The scientists scrutinized CHIME’s six years of data and found nothing: This new FRB seems to be a unique occurrence, at least within the last six years. The findings are especially thrilling, given the burst’s proximity. Due to its closeness and extraordinary brightness, researchers can investigate the environment surrounding the burst for clues about the potential origins of a nonrepeating FRB.
“Currently, we are in the midst of an exploration regarding whether repeating and nonrepeating FRBs differ. These observations are piecing together fragments of the puzzle,” Masui states.
“There is evidence indicating that not all FRB progenitors are identical,” Andrew adds. “We are on the path to localize hundreds of FRBs each year. The aspiration is that a more extensive array of FRBs localized to their native environments can help unveil the entire spectrum of these populations.”
The development of the CHIME Outriggers was sponsored by the Gordon and Betty Moore Foundation and the U.S. National Science Foundation. The establishment of CHIME was supported by the Canada Foundation for Innovation and the provinces of Quebec, Ontario, and British Columbia.